Insulin and C-peptide levels, pancreatic beta cell function, and insulin resistance across glucose tolerance status in Thais

Examining the Effect of a Novel Stress Reduction Intervention on the Control of Prediabetes: A Feasibility Study

BackgroundPrediabetes is a major risk factor for type 2 diabetes (T2D) and cardiovascular disease. Although prediabetes is associated with chronic stress-related behavioral and physiological maladaptation, few studies have focused on chronic psychological stress.PurposeThis study aimed to examine the feasibility and preliminary outcomes of Emotional Awareness and Expression Treatment (EAET) adopted and implemented among adults with high risk for prediabetes.MethodThis study used a prospective, within-subjects, repeated measures, uncontrolled design with a 4-week virtual intervention period and three measurement points for all participants: baseline, 3 months from baseline, and 6 months from baseline. Forty individuals were screened for prediabetes, and sixteen were eligible to participate. Divided into three groups, participants received four weekly virtual sessions of EAET. Glycated hemoglobin (A1C) and insulin secretion (C-peptide) were measured at baseline, 3- and 6-month periods in addition to self-reported eating habits, physical activity, and perceived stress.ResultsTwelve participants completed all sessions and were fully engaged in the intervention sessions. Across the study period, participants' perceived stress and unhealthy eating habits decreased significantly. Glycated hemoglobin (A1C) showed a non-significant drop at 6 months, but the average C-peptide concentration, exercise frequency, and exercise duration increased significantly.ConclusionsThe EAET stress reduction intervention is feasible and showed promising results in reducing stress and decreasing risk factors for T2D. EAET can be further developed to reduce the incidence and prevalence of T2D, which could lead to a significant decrease in the direct and indirect health and cost burdens of T2D.

Identification of a Novel Mitochondrial tRNA Mutation in Chinese Family with Type 2 Diabetes Mellitus

Background

Mutations in mitochondrial tRNA (mt-tRNA) could be the origin of some type 2 diabetes mellitus (T2DM) cases, but the mechanism remained largely unknown.

Aim

The aim of this study was to assess the impact of a novel mitochondrial tRNACys/tRNATyr A5826G mutation on the development and progression of T2DM.

Methods

A four-generation Han Chinese family with maternally inherited diabetes underwent clinical, genetic and biochemical analyses. The mitochondrial DNA (mtDNA) mutations of three matrilineal relatives were screened by PCR-Sanger sequencing. Furthermore, to see whether m.A5826G mutations affected mitochondrial functions, the cybrid cell lines were derived from three subjects with m.A5826G mutation and three controls without this mutation. ATP was evaluated by luminescent cell viability assay, mitochondrial membrane potential (MMP), and reactive oxygen species (ROS) were determined by flow cytometry. The student's two-tailed, unpaired t-test was used to assess the statistical significance between the control and mutant results.

Results

The age at onset of diabetes in this pedigree varied from 40 to 63 years, with an average of 54 years. Mutational analysis of mitochondrial genomes revealed the presence of a novel m.A5826G mutation. Interestingly, the m.A5826G mutation occurred at the conjunction between tRNACys and tRNATyr, a very conserved position that was critical for tRNAs processing and functions. Using trans-mitochondrial cybrid cells, we found that mutant cells carrying the m.A5826G showed approximately 36.5% and 22.4% reductions in ATP and MMP, respectively. By contrast, mitochondrial ROS levels increased approximately 33.3%, as compared with the wild type cells.

Conclusion

A novel m.A5826G mutation was identified in a pedigree with T2DM, and this mutation would lead to mitochondrial dysfunction. Thus, the genetic spectrum of mitochondrial diabetes was expanded by including m.A5826G mutation in tRNACys/tRNATyr, our study provided novel insight into the molecular pathogenesis, early diagnosis, prevention and clinical treatment for mitochondrial diabetes.

C-peptide is a predictor of telomere shortening: A five-year longitudinal study

AIM

Relative telomere length (RTL) predicts the development of many age-related diseases. Yet, few studies have evaluated their longitudinal effect on RTL. We investigated longitudinally the association between cardiometabolic risk factors and RTL.

METHODS

This was a longitudinal study with a 5-year follow-up period, based on data collected in 2014 and 2019. Of 478 participants in 2014, 198 consented to be followed-up in 2019. The associations between RTL and risk factors were analyzed using t-test, ANOVA or simple linear regression as applicable.

RESULTS

RTL was significantly shortened after 5 years (P<0.001). Older age (P=0.018) and gender (P=0.05) were significantly associated with shorter RTL at follow-up. Higher baseline C-peptide correlated with shorter RTL (P=0.04) and shortening of RTL (P=0.03) after 5 years. Multivariate linear regression including both age and gender revealed a significant trend for C-peptide and change in RTL after 5 years (P=0.04). Interestingly, there was a trend of shorter RTL at follow-up with diabetes, though the findings were not statistically significant.

CONCLUSIONS

Higher C-peptide level contributes to telomere shortening over time, suggesting that metabolic dysregulation may play a role in early aging. Further understanding of this relationship and addressing high C-peptide levels can be important to prevent premature aging.

Late onset of type 2 diabetes is associated with mitochondrial tRNATrp A5514G and tRNASer(AGY) C12237T mutations

Background

Mitochondrial dysfunctions caused by mitochondrial DNA (mtDNA) pathogenic mutations play putative roles in type 2 diabetes mellitus (T2DM) progression. But the underlying mechanism remains poorly understood.

Methods

A large Chinese family with maternally inherited diabetes and deafness (MIDD) underwent clinical, genetic, and molecular assessment. PCR and sequence analysis are carried out to detect mtDNA variants in affected family members, in addition, phylogenetic conservation analysis, haplogroup classification, and pathogenicity scoring system are performed. Moreover, the GJB2, GJB3, GJB6, and TRMU genes mutations are screened by PCR‐Sanger sequencing.

Results

Six of 18 matrilineal subjects manifested different clinical phenotypes of diabetes. The average age at onset of diabetic patients is 52 years. Screening for the entire mitochondrial genomes suggests the co‐existence of two possibly pathogenic mutations: tRNA^Trp A5514G and tRNA^Ser(AGY) C12237T, which belongs to East Asia haplogroup G2a. By molecular level, m.A5514G mutation resides at acceptor stem of tRNA^Trp (position 3), which is critical for steady‐state level of tRNA^Trp. Conversely, m.C12237T mutation occurs in the variable region of tRNA^Ser(AGY) (position 31), which creates a novel base‐pairing (11A‐31T). Thus, the mitochondrial dysfunctions caused by tRNA^Trp A5514G and tRNA^Ser(AGY) C12237T mutations, may be associated with T2DM in this pedigree. But we do not find any functional mutations in those nuclear genes.

Conclusion

Our findings suggest that m.A5514G and m.C12337T mutations are associated with T2DM, screening for mt‐tRNA mutations is useful for molecular diagnosis and prevention of mitochondrial diabetes.

Plasma C-Peptide and Risk of Developing Type 2 Diabetes in the General Population

C-peptide measurement may represent a better index of pancreatic β-cell function compared to insulin. While insulin is mainly cleared by liver, C-peptide is mainly metabolized by kidneys. The aim of our study was to evaluate the association between baseline plasma C-peptide level and the development of type 2 diabetes independent of glucose and insulin levels and to examine potential effect-modification by variables related to kidney function. We included 5176 subjects of the Prevention of Renal and Vascular End-Stage Disease study without type 2 diabetes at baseline. C-peptide was measured in plasma with an electrochemiluminescent immunoassay. Cox proportional hazards regression was used to evaluate the association between C-peptide level and type 2 diabetes development. Median C-peptide was 722 (566-935) pmol/L. During a median follow-up of 7.2 (6.0-7.7) years, 289 individuals developed type 2 diabetes. In multivariable-adjusted Cox regression models, we observed a significant positive association of C-peptide with the risk of type 2 diabetes independent of glucose and insulin levels (hazard ratio (HR): 2.35; 95% confidence interval (CI): 1.49-3.70). Moreover, we found significant effect modification by hypertension and albuminuria (p < 0.001 and p = 0.001 for interaction, respectively), with a stronger association in normotensive and normo-albuminuric subjects and absence of an association in subjects with hypertension or albuminuria. In this population-based cohort, elevated C-peptide levels are associated with an increased risk of type 2 diabetes independent of glucose, insulin levels, and clinical risk factors. Elevated C-peptide level was not independently associated with an increased risk of type 2 diabetes in individuals with hypertension or albuminuria.

C-peptide levels and the risk of diabetes and pre-diabetes among Chinese women with gestational diabetes

AIMS

To examine the association of connecting peptide (C-peptide) and the risks of postpartum diabetes and pre-diabetes among women with prior gestational diabetes.

METHODS

A cross-sectional study of 1263 women with prior gestational diabetes was carried out at 1-5years after delivery in Tianjin, China. Logistic regression was used to assess the associations of C-peptide and the risks of diabetes and pre-diabetes.

RESULTS

The multivariable-adjusted odds ratios based on different levels of C-peptide (0-33%, 34-66%, 67-90%, and >90% as C-peptide cutpoints) were 1.00, 1.93 (95% confidence interval [CI] 0.85-4.39), 2.49 (95% CI 1.06-5.87), and 3.88 (95% CI 1.35-11.1) for diabetes (P for trend <0.0001), and 1.00, 1.66 (95% CI 1.18-2.36), 2.38 (95% CI 1.56-3.62) and 2.35 (95% CI 1.27-4.37) for pre-diabetes (P for trend <0.0001), respectively. Restricted cubic splines models showed a positive linear association of C-peptide as a continuous variable with the risks of type 2 diabetes and pre-diabetes. The positive association was significant when stratified by healthy weight and overweight participants.

CONCLUSIONS

We found a positive association between serum C-peptide levels and the risks of diabetes and pre-diabetes among Chinese women with prior gestational diabetes. Our finding suggested that elevated C-peptide levels may be a predictor of diabetes and pre-diabetes.

Prevalence of insulin resistance and its relationship with cardiovascular disease risk factors among Thai adults over 35 years old

AIMS

To estimate the prevalence of insulin resistance (HOMA-IR) and to study its relationship with selected cardiovascular disease risk factors among Thai adults.

METHODS

This cross-sectional study was comprised of 227 men and 990 women undergoing routine health check-up. The prevalence of insulin resistance was estimated using diagnostic criteria previously employed in Asian and other populations. Spearman's rank correlation coefficients were used to evaluate associations of HOMA-IR with selected cardiovascular disease risk factors. Multivariable logistic regression procedures were used to evaluate associations of hypertriglyceridemia, low HDL-Cholesterolemia, and hypertension with varying HOMA-IR values.

RESULTS

Approximately 25.1% of men (HOMA-IR>or=1.56) and 21.5% of women (HOMA-IR>or=1.64) were classified as having insulin resistance. HOMA-IR values were statistically significantly and positively associated with body mass index, body fat percentage, waist circumference, and serum triglycerides. The values were inversely correlated with HDL-Cholesterol. When compared with those whose HOMA-IR values were within the lowest quartile (<0.45), men with HOMA-IR values in the highest quartile (>or=1.58) had higher risks of hypertriglyceridemia (adjusted OR=2.83), low HDL-Cholesterolemia (adjusted OR=2.79), and hypertension (adjusted OR=2.76). Similar associations were observed among women.

CONCLUSION

Insulin resistance, as determined using HOMA-IR, was positively associated with selected cardiovascular disease risk factors among Thai adults.